Bending the edges of sheet or plate stock

ABSTRACT

The edges of plates or sheets are bent by dies or rolls having coacting profiles which are essentially sections of similar circular involutes. The same set of tools can be used for bending the edges of differently thick stock requiring pivotal adjustment of the convexly contoured die or roll about an axis parallel to the bending axis. That adjustment may have to be supplemented by lateral adjustment of the concave die or roll (axial in the case of the latter). Different radii of bending curvature are obtained by different degrees or lengths of insertion of the plate stock between the dies or rolls.

[4 1 Oct. 14, 1975 BENDING THE EDGES OF SHEET OR PLATE STOCK Walter Randerath, Viersen, Germany [75] Inventor:

[73] Assignee: Mannesmann Aktiengesellschaft,

Dusseldorf, Germany 22 Filed: Oct.1l, 1974 [2l] Appl. No.: 513,955

1,649,613 11/1927 Olson 72/179 X 3,159,199 12/1964 Ruple i 72/178 3,472,053 10/1969 Chang 72/178 Primary ExaminerMilt0n S. Mehr Attorney, Agent, or FirmRalf H. Siegemund ABSTRACT The edges of plates or sheets are bent by dies or rolls having coacting profiles which are essentially sections of similar circular involutes. The same set of tools can F'Al't'Pr"tDta [3O] orelgn pp lca Ion Ion y a be used for bending the edges of differently thick Oct. 17.1973 Germany 2352573 Stock requiring pivotal adjustment of the Convexly contoured die or roll about an axis parallel to the [52] bending axis. That adjustment may have to be supple- [51] '3 C mented by lateral adjustment of the concave die or [58] Field of Search 72/ 25 roll (axial in the case of the latter). Different radii of 7 bending curvature are obtained by different degrees or lengths of insertion of the plate stock between the dies [56] References Cited or tons UNITED STATES PATENTS l,585,696 5/1926 Smith 72/179 9 Chums 8 Drawmg guns f0 7/ll n[\L 0 5 Li y US. Patent 00. 14, 1975 Sheet 2 of5 3,911,709

K I J U.S. Patent Oct. 14, 1975 Sheet 3 of5 3,911,709

U.S. Patent Oct. 14, 1975 Sheet 4 of5 3,911,709

U.S. Patent 0a. 14, 1975 Sheet 5 of5 3,911,709

BENDING THE EDGES OF SHEET OR PLATE STOCK BACKGROUND OF THE INVENTION The present invention relates to bending of sheets or plates in preparation of blanks to be used for making cylindrical hollow bodies, particularly seam welded steel tubes or pipes. More particularly, the invention refers to tooling for bending of sheets or plates in which one die or roll has convex contour cooperating with a complementary die or roll having concave contour.

Steel sheets or plates have to be bent near their edges to assume the radius of the pipe or tube to be made so that the subsequent tube bending places the edges into properly azimuthally aligned abutting position to obtain a split tube to be seam welded along these abutting edges. The dies used here bend rather thick plates over the entire length in one bending step.

No difficulties are posed by the requirement for a die that will bend the edges of a plate having a particular thickness so as to obtain a particular radius of curvature. The gap between upper and low die will remain constant over the entire range of bending. That, however, remains true only for a radius and a plate thickness. A different radius and/or a differently thick plate can be worked in that fashion only with a different set of dies. If a particular press tool is to work indeed different plates into blanks for different pipes, one needs a correspondingly large set of different dies, and any change in the desired product requires time consuming exchanges of the dies. Consequently, one has occasionally compromised and used the same set of dies for differently thick plates, the gap between the dies was not constant in that case.

DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a tool for bending the edge-near portions of differently thick plates and for different radii of curvature, but using the same set of dies or other forming element without compromise as to constancy of the gap width between convex and concave tool parts.

In accordance with the present invention it is suggested to provide the two tools respectively with convex and concave contour being in each case one and the same portion of a circular involute. Such sets of dies or of a corresponding set of contoured rolls can indeed bend differently thick plates along an edge to obtain similar or differently curved edges, with constancy of the gap in each instance.

In furtherance of the invention the convex die or roll should be pivotal or tiltable on an axis which runs parallel to the bending axis and which can be arrested and locked in a number of different tilt positions. It must be observed that the tool requires two sets of dies or rolls, one for each edge. The two convexly contoured dies or rolls have therefore, parallely disposed tilt axes lying in a common plane. The two concavely contoured dies or rolls are reciprocatively positioned for movement towards or away from each other, parallel to that plane.

DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:

FIG. I is a front view of a plate edge bending machine with dies in accordance with an example of the preferred embodiment of the present invention;

FIG. 2 shows one pair of bending dies in closed position, no plate being inbetween;

FIG. 3 shows the same pair of dies in a disposition for a plate or sheet having thickness S;

FIG. 4 shows the lower die of the pair with explanatory markings as to the geometry involved;

FIG. 5 shows that pair of dies for bending a plate at one edge with a rather small radius of curvature;

FIG. 6 shows these dies for a medium radius of curvature of bending;

FIG. 7 shows these dies for a large radius of curvature of bending; and

FIG. 8 shows an alternative example using rolls tool.

Proceeding now to the detailed description of the drawings, the edge bending equipment shown in FIG. 1 works on two opposing edges of a thick steel sheet or plate 30 seen in that Figure in edge-on view but along the axes of bending. Two sets of dies 1, I are provided in two C-shaped frames or stands 5 and 5 having their respective open sides face each other.

The die set 1 in frame 5 is comprised of upper and lower dies 2 and 3 respectively; the set 1 in frame 5' has corresponding upper and lower dies 2' and 3. Upper dies 2 and 2' have symmetrically arranged convex contours; lower dies 3, 3' have symmetrically arranged concave contours.

bower dies 3, 3 are supported by tool carriers 4, 4 and are respectively laterally movable relative thereto, particularly in the horizontal direction parallel to the plane of the drawing in FIG. 1, so that each die 3 and 3 is respectively movable laterally as to its vertical alignment with die 2, 2' and independantly from the respective other set of dies.

Movement is provided for respectively by means 7, 8 for die 3, which may be hydraulic actuators for moving and positioning die 3 on carrier 4. Alternatively, the lower dies may be laterally displaced by means of adjustment spindles 7 and 8 as shown in FIG. 2, to obtain e.g. micrometer like adjustment in the disposition of lower die 3 on carrier 4. Analogous actuators operate die 3' in carrier 4.

The tool or die carrier 4 is secured to a hydraulic piston/cylinder arrangement 6 for up and down movement. Carrier 4' is analogously operated in frame 5. These piston/cylinder drives provide the main power for the bending of the two edges of sheet 30 as stated. Particularly, the lower dies serve as rams which push the edges of a plate up against the respective upper die to obtain conformity of contour with the die contours. The bending operation could be carried in down direction.

The upper die 2 is held by pivot arm 19 which is journalled on a shaft or bolt 13 for pivoting or tilting about horizontal axis II. The upper die 2' is held by a similar pivot arm, also being joumalled on a bolt for pivoting about an axis 11'. The two axes 11, 11 extend parallel to each other and both extend transverse to the plane of the drawing. Reference numerals l2, l2 refer respectively to hydraulic actuators for moving, i.e., tilting the upper dies 2, 2' and holding them in the respective tilt position. Positive mechanical locks may additionally provide for position arresting and holding the dies against bending pressure.

The two C-frames and 5 are mounted on or constructed as carriages running on rails 9 so as to adjust the distance between the two edge bending tools to the width of the sheets or plate, and to determine the extent of insertion of a plate edge between the dies of a set.

Turning now to details of the edge bending equipment, reference is made more specifically to FIGS. 2, 3 and 4. FIGS. 2 and 3 in particular show a pair of dies wherein the convex contour 17 of upper die 2 and the concave contour 16 of lower die 3 are essentially portions of the same circular involute. FIG. 4 shows that involute per se on the lower die 3.

The development of a circular involute and of a particular position thereof and with a desired smallest radius rl is a mathematical problem that can be solved on the basis of computation or graphically. FIG. 4 is an example of an involute with three radii, rl, r2, r3 being particularly indicated. That number is arbitrary and additional once between a largest (r3) and the smallest (rl could well be indicated because the involute provides for continuous transition from a smallest radius rl to a largest radius r3.

FIG. 2 shows upper die 2 seated on lower die 3 and one can say that between upper and lower contours l6,

l7 there is a gap of width zero throughout. An operating position is established when a finite gap exists between the two dies, such shown in FIG. 3, the gap width being S, measured by and along normals on the respective die contour faces (16, 17).

The disposition of the dies 2, 3 in FIG. 3 is obtained, beginning with the disposition of FIG. 2, in that upper die 2 is tilted about its pivot axis 11 of a fixed bolt I3. The initial tilt position of FIG. 2 is indicated in FIGS. 2 and 3 by a dash dot line 14, representing for example a straight down hanging disposition of upper die 2. The die 2 on arm 19 is tilted by operation of the tilt actuator 12 in direction of arrow 15 until a tilt position defined by 14' is obtained. The tilt angle is indicated by the two arrows 20.

In addition to tilting the upper die, lower die 3 is laterally (horizontally) displaced in direction of arrow 21. The particular combination of lateral displacement and tilting establishes a particular value for gap S whose width is indeed constant throughout the upper-lower die combination.

FIG. 3 shows of course, the final disposition of the dies when bending a sheet. That disposition is obtained after the downwardly retracted die 3 has been pushed up by the vertical drive 6. The originally plane plate 30 is thereby bent up and forced against upper die 2, and the FIG. 3 shows the final disposition of the dies when the edge of a sheet or plate of thickness S has been bent by having been forced to adapt to the contours of the upper and lower dies.

For purposes of completion only, it should be mentioned that the final disposition of the dies relative to 7 each other and out of a disposition shown in FIG. 2, re-

ment with bent up portions of plate 30 upon completion of bending.

It should be mentioned at this point that pivot and tilt axis ll of die 2 could be placed in the center of the base circle of the circular involute as defining contour 17 for a disposition of die 2 given by 14. In that case, pivoting of the upper die suffices for adapting the die to any particular plate thickness, the lower dies do not have to be laterally shifted. However, constructing the dies in that manner may require to place pivot axis I] quite far from die 2 so that additional construction complications may be encountered. Therefore, a combination of upper die tilt and lower die lateral displacement was found simpler and is preferred.

An alternative solution is to guide the pin 13 in a cam structure of frame 5 to thereby simulate pivoting about the center of the base circle of the circular involute as holder 19 pivots actually on axis 11.

It should be mentioned further that contours 16, 17 are sections of one and the same circular involute to the extent they do overlap. However, upper die 2 and its contour 17 extends somewhat beyond contour 16 to obtain dependancy on the plate thickness range to be covered by this set of tools (dies). Therefore, the statement that contours l6, 17 match essentially has to be understood in this context.

FIGS. 5, 6 and 7 now illustrate how a plate of the same thickness (tilt/lateral displacement adjustment of being the same) can be bent at its edges to a different radius of curvature. FIG. 7 can be understood also as a view of a detail of FIG. 1 on an enlarged scale, as sheet 30 in Figure is bent as indicated in detail in FIG. 7.

The sheet 28 of FIG. 5 (or 27 of FIG. 6) is to be gripped by the edge bending tool so that the edge proper 29 of that sheet reaches exactly to the radius of smallest curvature to be obtained. From that point the radius increases until merging to the straight end of the involute.

It can readily be seen that the plate 28 in FIG. 5 has its edge bent to the smallest radius r, of the involute. The edge of plate 27 in FIG. 6 is bent to a radius somewhat larger, while plate 30 is bent to radius r2.

It can thus be seen that tilt adjustment, possibly together with lateral adjustment of the lower die matches and adapts the die set to the thickness of the plate whose edges are to be bent. This is an adjustment carried out in each frame 5, 5 independantly. Shifting the frames 5, 5 towards or away from each other does not only adapt the system to the width of the sheets or plate, but also to the radius of bending, i.e., to the degree of lateral insertion of the plate into each set of dies. That adjustment however, must take the plate thickness into consideration. Any effective radius of curvature of the lower die will, in the adjusted final disposition, be radially aligned with a particularly effective radius of curvature in the upper die. That latter radius will be reduced by the thickness or gap width S as compared with the former, so that radially aligned contour radii of the two contours have the same center of curving.

The following table shows dimensions of a lower die corresponding to FIG. 4, the upper die has corresponding dimensions. The die width b was 285 mm for bending an edge portion of a plate which is at least 1/15 of the final pipe periphery. The resulting smallest pipe to be made may-have a diameter of 24 inches so that the smallest radius of curvature in the involute should be half that value or 12 inches. The largest pipe to be made could be 35 inches in diameter so that the largest involute radius to be used is about 17.5 inches. The largest involute radius present will then be about 24 inches.

FIG. 8 shows an alternative mode of practicing the invention. Rather than having dies one could use contoured and profiled rolls. Accordingly, a roll 2a may have bulging contour of the circular involute type as to its profile. Roll 3a is correspondingly concave. These rolls are mounted or journalled shafts 22, 23. Particularly, roll 2a is mounted on shaft 22 but in a manner permitting pivoting on an axis of a bolt 24 which intersects the axis of shaft 22. The roll 2a, therefore, can be tilted for the same purpose die 2 is tiltably mounted.

Roll 3a is mounted for axial displacement on shaft 23 (arrow 18) and shaft 23 can be displaced relative to roll axis 22, as indicated by arrow 25. This way, the rolling gap is adapted to the plate thickness. The relative position of the roll stand to the sheet or plate determines again the effective smallest radius of bending.

It can readily be seen that the same set of tooling can be used for bending the edges of differently thick plates or sheets and bending is made possible for different smallest radius of curvature at the edges of the sheet or plate so prepared for further working it into a pipe.

The invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the spirit and scope of the invention are intended to be included.

I claim:

1. Device for bending the edges of sheet or plate stock, for example, in preparation of making seam welding pipes or tubes, comprising:

a first tool with a convex contour being a section of a circular involute and being mounted for pivoting on an axis parallel to an axis of bending;

a second tool with a concave contour being a section of essentially the same circular involute, the first and second tools being mounted for lateral displacement relative to each other transverse to said axis; and

means for adjusting the final working disposition between upper and lower tool including pivoting of the first tool relative to the second tool and lateral displacement of said tools relative to each other prior to a bending operation for obtaining constant gap width as between the two contours, said tools being held in their respective adjusted position during bending.

2. Device as in claim 1, wherein a similar set of concave and convex tools is provided symmetrical to the first mentioned tools for concurrent bending of opposite edges of the sheet stock, the two sets of tools being adjustible relative to each other, the two convexly contoured tools being pivotable respectively about two parallel axes.

3. Device as in claim 2, the concavely contoured tools being adjustible parallel to a plane as defined by said two parallel axes.

4. Device as in claim 1, wherein the first tool is an upper die, the second tool being a lower die, further including hydraulic means for moving upper and lower dies towards each other, the upper die being mounted for pivotal adjustment of its disposition relative to the lower die.

5. Device as in claim 4, wherein the lower die is mounted on a tool carrier and being laterally adjustible relative thereto.

6. Device as in claim 5, wherein said hydraulic means operates said tool carrier.

7. Device as in claim 1, wherein tools are contoured rolls respectively with convex and concave periphery, the axes of the rolls having adjustible distance from each other.

8. Device as in claim 7, wherein the roll having the convex periphery is pivotally mounted for tilting on an axis intersecting its roll axis.

9. Device as in claim 8, wherein the roll having the concave periphery is mounted on a shaft for axial displacement therein. 

1. Device for bending the edges of sheet or plate stock, for example, in preparation of making seam welding pipes or tubes, comprising: a first tool with a convex contour being a section of a circular involute and being mounted for pivoting on an axis parallel to an axis of bending; a second tool with a concave contour being a section of essentially the same circular involute, the first and second tools being mounted for lateral displacement relative to each other transverse to said axis; and means for adjusting the final working disposition between upper and lower tool including pivoting of the first tool relative to the second tool and lateral displacement of said tools relative to each other prior to a bending operation for obtaining constant gap width as between the two contours, said tools being held in their respective adjusted position during bending.
 2. Device as in claim 1, wherein a similar set of concave and convex tools is provided symmetrical to the first mentioned tools for concurrent bending of opposite edges of the sheet stock, the two sets of tools being adjustible relative to each other, the two convexly contoured tools being pivotable respectively about two parallel axes.
 3. Device as in claim 2, the concavely contoured tools being adjustible parallel to a plane as defined by said two parallel axes.
 4. Device as in claim 1, wherein the first tool is an upper die, the second tool being a lower die, further including hydraulic means for moving upper and lower dies towards each other, the upper die being mounted for pivotal adjustment of its disposition relative to the lower die.
 5. Device as in claim 4, wherein the lower die is mounted on a tool carrier and being laterally adjustible relative thereto.
 6. Device as in claim 5, wherein said hydraulic means operates said tool carrier.
 7. Device as in claim 1, wherein tools are contoured rolls respectively with convex and concave periphery, the axes of the rolls having adjustible distance from each other.
 8. Device as in claim 7, wherein the roll having the convex periphery is pivotally mounted for tilting on an axis intersecting its roll axis.
 9. Device as in claim 8, wherein the roll having the concave periphery is mounted on a shaft for axial displacement therein. 